Mechanical properties of polymer-modified silica aerogels dried under ambient pressure

Lightweight foams of amine-rich organosilica and cellulose nanofibrils by foaming and controlled condensation of aminosilane

“…as thermal and acoustic insulation materials, 2 CO 2 3 and oil sorbents, and water purification filters. 4 Organosilica foams can be produced in several ways, including sol-gel processing of an organofunctional silane (OS), [5][6][7] co-gelation of an OS with tetra-alkoxysilanes 8,9 or post-modification of silica alcogels. 10 The sol-gel processing of the OS is done in a multistep (i to iv) process involving the use of an alcohol-water mixed solvent.…”

“…21 Other processing techniques have thus been investigated, which include the use of solvents with reduced surface tension (e.g. isopropanol/n-hexane, 13 N,N-dimethylformamide 6 and ethanol/heptane 25 ), in situ polymerization in organosilica gel 8,26,27 or direct polymer addition 28,29 to an OS solution. 2 In situ polymerization in wet silica gels can lead to the formation of a strongly cross-linked polymer/silica network, resulting in a monolithic aerogel with limited shrinkage (16%).…”

“…2 In situ polymerization in wet silica gels can lead to the formation of a strongly cross-linked polymer/silica network, resulting in a monolithic aerogel with limited shrinkage (16%). 8 By direct polymer addition, the chemical bonds formed between the OS and the polymer 28 or tetraalkoxysilane and OS modified polymer 30 can restrict the mobility of the wet silica network upon evaporation and limit the shrinkage and cracking of the material. However, the best control and preservation of the foam shrinkage and structure has so far been achieved by combining techniques that includes the use of polymers and organic solvents (in particular, isopropanol 30 or acetone 8 ) or the post-hydrophobization of the alcogel/polymer using an OS.…”

Preparation and characterization of polyurethane/silica aerogel nanocomposite materials

“…In recent years and after the production of silica aerogels under ambient pressure drying (APD) condition by Deshpande et al . in 1993, numerous researches and developments have taken place on silica aerogel and its composites . Such endeavors could be categorized into three main branches; first are the ones aimed at reducing production cost through synthesizing in ambient pressure and also utilizing cheaper initiating materials such as water‐glass .…”

Microstructure and properties of the Si3N4/silica aerogel composites fabricated by the sol–gel method via ambient pressure drying

“…To overcome these problems, improvement of the strength and thermal stability is necessary. Many efforts have focused on improvement of the mechanical properties of the silica aerogels by using structural reinforcement [5][6][7], fiber reinforcement [8][9][10], polymer cross-linking [11][12][13][14] or other chemical or physical means [15][16][17][18][19]. However, it is difficult to form the fiber-reinforced silica aerogel composites into complex shapes.…”